In the vast field of materials science, two-dimensional (2D) material has long been a focal point of cutting-edge research. Since the discovery of single-layer graphene in 2004—an event akin to dropping a massive stone into a calm lake, sending ripples in all directions—the family of 2D materials has rapidly expanded. To date, hundreds of experimentally accessible 2D materials have been identified. However, for a long time, these 2D materials were largely confined to layered material systems. Metals, which hold a significant position in the materials world, are mostly non-layered materials. Reshaping metals into 2D forms has thus posed a major challenge to the scientific community.
A research team from the Chinese Academy of Sciences has achieved a groundbreaking breakthrough in addressing this challenge, with molybdenum disulfide (MoS?)—seemingly ordinary yet extraordinarily remarkable—serving as the key to unlocking this puzzle.
2D materials, characterized by their thickness of just a single atomic layer or a few atomic layers, stand out uniquely in materials science. This ultrathin structure breaks the conventional mold of traditional materials, opening up entirely new dimensions of exploration. In condensed matter physics, 2D materials act like a key, unlocking the mysterious treasure chest of quantum mechanics in low-dimensional spaces. The extreme thinness of atomic layers reshapes electron behavior, confining their motion to a 2D plane and significantly enhancing electron-electron interactions. This gives rise to exotic phenomena such as the quantum Hall effect. These discoveries deepen our understanding of microscopic physical laws and lay a solid foundation for innovations in quantum electronic devices.
In materials science, 2D materials offer an exceptionally high specific surface area due to their atomic-scale thickness, far surpassing traditional materials in terms of surface-active sites. This property enables them to accelerate reaction rates with high precision and selectivity in catalytic reactions, and to rapidly capture specific gas molecules in gas adsorption, aiding environmental monitoring and gas separation. Owing to their immense potential across multiple fields, 2D materials have become a global research hotspot, continuously driving technological innovation and progress.
The researchers noted, “Unlike layered materials, where atoms in metal materials are strongly bonded to surrounding atoms in all directions via metallic bonds, the challenge is evident. If layered materials are likened to a ‘layered pastry,’ metal materials are more like a ‘compressed biscuit.’ Therefore, reshaping metal materials into 2D forms is far more difficult than with layered materials.”
In this pioneering study, the research team ingeniously utilized molybdenum disulfide. They first melted the metal and then employed a high-quality single-layer MoS? anvil, meticulously prepared by the team in earlier work, to perform a pressing operation. This innovative approach successfully enabled the universal preparation of various 2D metal material. Metals such as bismuth, tin, lead, indium, and gallium, with the “assistance” of MoS?, underwent a remarkable transformation from their conventional state to a 2D state, achieving thicknesses as thin as one two-hundred-thousandth of a hair’s diameter.
It is reported that the 2D metal material prepared by the Chinese Academy of Sciences team not only achieved a significant increase in lateral dimensions but also demonstrated excellent environmental stability, showing no performance degradation in experimental tests spanning over a year. This achievement received high praise from reviewers of the international academic journal Nature, who recognized it as a powerful advancement in the field of 2D metal material and a significant milestone in 2D materials research.
2D metal material holds vast application prospects, poised to drive technological breakthroughs in areas such as ultra-miniature low-power transistors, high-frequency devices, transparent displays, ultra-sensitive detectors, and highly efficient catalysis. Behind all these accomplishments, molybdenum disulfide plays an indispensable role. With its unique structure and properties, it has made the transformation of metal materials into 2D structures possible, emerging as a critical force in opening the door to the new world of 2D metal material.
